Do we now know why ozone is harmful?

In the upper atmosphere, ozone shields the Earth from ultraviolet rays. But lower down, it can be harmful to respiratory systems, and in recent years scientists have documented increases in heart problems associated with ozone.

Chronicle

Not just an unsightly blight.

That’s all bad news for Houston, of course, because it regularly has the second-worst ozone pollution behind only Los Angeles. According to one state agency, each year, millions of people in the greater Houston area are exposed to unhealthy levels of ozone at one point or another.

But what scientists didn’t really know, until now, is how the inhaled pollutant caused damage. A new study in mice may have found the answer, that inhaled ozone impairs the body’s immune system. From a summary:

The Duke-led team found that ozone exposure in mice at levels approximating unhealthy levels for humans appears to enhance lung injury in response to bacterial toxins, but more importantly, it also appears to enhance programmed cell death in critical innate immune system cells that gobble up foreign invaders, keeping the airways clear.

“Small amounts of inhaled foreign material can be relatively harmless, since they stimulate an appropriate innate immune response that protects the lungs,” said John Hollingsworth, M.D., pulmonologist and lead author of a study whose results appear Oct. 1 in the Journal of Immunology. “However, it appears that ozone causes the innate immune system to overreact, killing key immune system cells, and possibly making the lung more susceptible to subsequent invaders, such as bacteria.”

The innate immune system is the most primitive aspect of the body’s defenses. Its cells react indiscriminately to any invader. One of the key cells in the innate immune system is known as a macrophage, Greek for “big eater.”

17 Responses

No doubt a factor in why some people who have never smoked contract lung cancer. Let’s all just hold our breath until at least 2018.

Eric, one of the links you included showed Ozone levels for verious metro areas in Texas. The number given for Houston was 38 yet when you click on that icon for specifics on reporting locations in the Houston area none of them comes anywhere close to being as high as that summary 38 number for the overall metro area. Is a puzzzlement.

Yes, O3 is a dangerous air pollutant, I gasp and cough whenever we have orange alerts. It kills people. Why don’t we put a little of the overexposure and overzealousness of AGW hysteria and funding and lobbying toward something that really makes a difference in real time? I know, Al Gore, Sheryl Crow, Babs Boxer, etc. are not worried about O3, not trendy and “political” enough to worry about. So where are our real priorities as a society? Sad.

Other well know O3 impacts on the respiratory system–bronchial constriction, etc. Also, smog consists of more than just O3, though for convenience only O3 is monitored. If one includes other photochemical oxidants–e.g., aldeyhydes, nitric oxide, nitrogen dioxide, etc., there are many profound health impacts. Interestingly, asthma may be more affected by inside air chemicals (e.g., formaldehyde), cigarette smoke, and mold, than by outside air pollutants.

Eric, sorry again over the all the white space in my above comments. I am losing track of spacing because I have trouble seeing the little tiny SciGuy comment box on my screen! I will tighten up the spacing here.

The Boston metro area used to look like the picture until the original Clean Air Act started to take effect. Now it is very rarely anywhere near that bad. Why the program worked there and not in Houston I have no idea.

According to the linked story, state officials say Houston will meet the standards by 2018 at the latest, not 2018 at the earliest. But, that’s the current standard. The EPA is in the public comment phase of a proposal to make the federal ozone standards stricter, possibly much stricter. See here and here here for EPA materials, or read a recent news article from another Texas newspaper. (Sorry, can’t find the relevant Chronicle article in the online archive.)

For one thing, it’s a lot hotter here in the summer than in Boston, which averages a mere 82 in July.

But the main reason appears to be the petrochemical industry along the ship channel, which has a unique chemistry that doesn’t show up in other US metros.

A Brookehaven study 4 or 5 years back showed that there is a very high concentration of VOCs from propene, butene and ethene along the ship channel which cause excessive ozone production. The high concentration of petrochemical facilities along the channel apparently produce several times the amount of ozone than the other sources in the metro.

There is probably a story or three here in the Chron archives about it.

I’m watching the Upper Level Low, and anything that develops as a result might head toward Texas. Not too concerned at this point, but if by tomorrow the system looks like something may develop I’ll provide an update here.

That picture looks like the one taken when they were burning down the forests in Mexico and it all blew up here for about two months. For several days every week, the skyline is crystal clear, depending on the wind. It’s not always like that picture, especially in the cooler months from October to April.

“Why the program worked there and not in Houston I have no idea.” Posted by: Roger

Boston doesn’t cover 650 square miles and doesn’t have one the worlds’ largest refinery complexes and chemical makers, plus it sits in an Atlantic breeze. And it stays cold 9 months of the year. Regional comparisons don’t work for any amount of money thrown at it, scientific or not.